Wireless communication systems, such as cellular voice and data networks, typically include multiple wireless access nodes spread over a geographic area. As a result, wireless communication devices can register at various wireless access nodes and access communication services. In many examples, the wireless communication devices are mobile, and can move between wireless coverage areas of the wireless access nodes. As a result, people can use cellular telephones in a wide variety of locations and can make calls while moving or traveling.
Continuous cellular telephone service is available through handoffs, wherein an active cellular telephone can move from cell to cell in a cellular network. The cellular network hands off the cellular telephone from one base station to the next. As a result, a user receives continuous and uninterrupted service.
A handoff may occur where the cellular telephone is moving from one cell to the next and a handoff must be performed for the cellular telephone to maintain communications. Alternately, a handoff may occur where a cellular telephone is in a region overlapped by another cell and the cellular telephone is handed off to provide more capacity in the cell. In another alternative, a handoff may occur where a cellular telephone is experiencing interference in a current cell and is handed off to a neighboring cell to reduce interference.
In a handoff, an adjacent cell will be using a different set of frequencies in order to avoid interference. Consequently, during a handoff process, the cellular telephone must negotiate with both a current cell and a next cell over the transfer of service. Issues that must be addressed are the identity of the cellular telephone and the traffic load/capacity of the next cell, for example.
Overview
Systems and methods for contention-free handoff return in a wireless network are provided herein. In one example, a first enhanced Node B (eNB) for contention-free handoff return in a wireless network includes a transceiver system configured to communicate with a User Equipment (UE) and a processing system coupled to the transceiver system and configured to receive a signal strength and an interference information from the UE via the transceiver system, with the processing system being configured to obtain a pre-handoff CF preamble for handoff of the UE from the first eNB to a second eNB, provide the pre-handoff CF preamble to the UE, generate a post-handoff CF preamble for the UE, and provide the post-handoff CF preamble to the UE.
In an example of a contention-free handoff return method for a wireless network having a first enhanced Node B (eNB), the method includes in the first eNB, obtaining a pre-handoff contention-free (CF) preamble for handoff of the UE from the first eNB to a second eNB, in the first eNB, providing the pre-handoff CF preamble to the UE, in the first eNB, generating a post-handoff CF preamble for the UE, and in the first eNB, providing the post-handoff CF preamble to the UE.
In another example of a contention-free handoff return method for a wireless network having a first enhanced Node B (eNB), the method includes in the first eNB, obtaining a pre-handoff contention-free (CF) preamble for handoff of the UE from the first eNB to a second eNB, in the first eNB, providing the pre-handoff CF preamble to the UE, in the first eNB, comparing a first eNB signal strength of a signal received in the UE from the first eNB to a second eNB signal strength of a signal received in the UE from the second eNB, in the first eNB, generating a post-handoff CF preamble if a signal strength difference between the first eNB signal strength and the second eNB signal strength does not exceed a predetermined strength similarity range, and in the first eNB, providing the post-handoff CF preamble to the UE.